Asymmetric device and mounting means therefor



B. LAZICH ET AL ASYMMETRIC DEVICE AND MOUNTING MEANS THEREFOR A 4 9 1 32 V. M

Filed Feb. 12, 1942 EEC mh S m wwm 5 ma m W kH H f H 5 mm m M 9 nPatented May 23, 1944 AsrMME'mrc DEVICE AND MOUNTING Means 'rnnnnroaBranko Lazich, Wilkinsburg, and Richard B.

Williams, In, Pittsburgh, Pa assignors to The 1 Union Switch & SignalCompany. Swissvale, Pa., a corporation of Pennsylvania ApplicationFebruary 12, 1942, Serial No. 430,642

3 Claims.

Our invention relates to asymmetric devices and to mounting meanstherefor In certain forms of electrical control apparatus which havebeen proposed for effecting one function or another according as apolarized control circuit is energized by current'of one relativepolarity or the other, such for example, as the apparatus disclosed andclaimed in an application for Letters Patent of the United States,Serial No. 424,151, filed by Arthur E. Dodd on December 23, 1941, apolarrelay and an auxiliary relay are connected in series in the polarizedcontrol circuit through one or more elements of an asymmetric device anda polar contact of the polar relay, wherebythe auxiliary relay checksthe response of the polar relay to changes in the polarity of the energysupplied to the polarized control circuit.

One object of our present invention is to provide an asymmetric deviceconsisting of a novel assembly of asymmetric'units of the dry disc typefor use in control apparatus of the type described, together with animproved mounting base therefor through which external circuitconnections with the device may be made, said device and said mountingbase being so constructed that the device can be readily plugged inte-gr removed from the mounting base, and that, vi l hen the device isremoved from the mounting base any external circuits which are inmultiple with any part of the device will be broken;

Another object of our invention is to provide an asymmetric device ofthe type described with novel means for automatically locking it againstaccidental displacement from its proper operative position with respectto the mounting base.

A further object of our invention is to so arrange the connecting prongson the device and the cooperating contact clips in the mounting basethat slight differences in the spacing of the connecting prongs, due forexample to unavoidable differences in the thickness of the asymmetricunits, will not affect the proper cooperative relationbetween theconnecting prongs and the contact clips.

According to our invention, the device consists of a stack of asymmetricunits, preferably of the well known copper oxide variety, assembled ona. clamping bolt in a manner similar to that in which the asymmetricunits of a copper oxide rectifier are usually assembled, except for thefact that special contact plates are provided at each end of the stackand at one or more intermediate points in the stack. These contactplates are each provided with projecting contact prongs disposed atright angles to, and laterally offset from, the plane of the main bodyportions of the contact plates in such manner that by turning th contactplates around in the stack the distance between the contact plates canbe changed to increase or decrease the available space for asymmetricunit without changing the spacing between the contact prongs. At leastone of the contact plates is formed with a locking prong for cooperationwith a locking spring provided in the mounting base to lock the deviceagainst accidental displacement when it is plugged into the base.

The mounting base is designed to partially enclose the-device to protectit from injury, and is provided, in addition to the locking springreferred to above, with contact clips disposed in recesses forcooperation with the prongs of the contact plates of the device.

Other objects and characteristic features of our invention will becomeapparent as the description proceeds.

We shall describe two forms of asymmetricv devices embodying ourinvention, and one form of mounting base therefor, also embodying ourinvention, and shall then point out th novel features thereof in claims.

In the accompanying drawing, Fig. 1 is an isometric view showing anasymmetric device embodying our invention, together with its associatedmounting base also embodying our invention. substantially on the line11-11 of Fig. 1. Fig. 3 is a longitudinal sectional view of theasymmetric device shown in the preceding views. Fig. 4 is a top planview of the mounting base shown in Figs. 1 and 2 with certain of theparts broken away to better illustrate the construction of the remainingparts. Fig. 5 is an enlarged vertical sectional view of one of theasymmetric units forming part of the asymmetric device shown in Figs. 1,2 and 3. Fig. 6 is a view showing a modified form of the asymmetricdevice shown in the preceding views.

Similar reference characters refer to similar parts in each of theseveral views.

Referring to the drawing, an asymmetric device embodying our inventionis here shown as comprising a plurality of asymmetric units A of the drysurface contact variety, each consisting of a flat plate I of a metal,such as cop per, having a coating 2 of a compound of the metal, such ascopper oxide, formed thereon (see Fig. 5). Asymmetric units of the typedescribed exhibit the characteristic of offering Fig. 2 is a verticalsectional view taken a higher resistance to current which tends to flowfrom the copper to the oxide than to current tending to flow in theopposite direction through the unit.

The asymmetric units A are stacked on a clamping bolt 3 between twocontact plates .4 and 5, and a third contact plate 6 is inserted in thestack in a position to divide the stack into two parts or legs, eachpreferably containing the same number of units. A thin washer l of animpressionable electrical conducting material, such as lead, is placedadjacent the coating 2 of cuprous oxide of each unit, and interposed ineach leg of the stack are one or more spacer washers 8 which areprovided to obtain a predetermined spacing between the contact plates.As shown, the units in the two legs of the device all face in the samedirection, but the device may, where circuit requirements warrant it, beassembled with the units in the two legs facing in opposite directions,or by providing additional connectors not shown any arrangement ofmultiple connections within the physical limits of the apparatus may beobtained.

The units, the contact plates, and the yarious washers are all insulatedfrom the clamping bolt by a sleeve 30 of insulating material whichsurrounds the bolt, and by two insulating washers 9 and Ill. The washer9 is disposed on the bolt 3 between the head 3a of the bolt and thecontact plate 4, and is provided at its outer face with a metal pressuredistributing member 9a against I which a spring washer ll bears. Thewasher i is disposed on the bolt between the nut 3b and and the contactplate 5, and is similarly provided with a metal insert Illa againstwhich a spring washer l2 bears. The two spring washers Ii and I2 serveto maintain a uniform pressure on the parts, whereby the impressionableconducting plates are firmly pressed into intimate contact with theoxide coating of the units.

For many applications, it is desirable to be able to plug an asymmetricdevice of the type thus far described into a mounting base through whichexternal circuit connections with the device may be made, whereby thedevice can be quickly removed and replaced with a similar device withoutdisturbing the external circuit wiring. Furthermore, since in manyapplications the two legs of the device are connected in multiple withvarious circuit apparatus it is desirable to insure that when the deviceis removed from the mounting base, all multiple circuits will be broken.To this end, we provide each contact plate with two integral prongs aand b located on opposite sides of the plate. These prongs are disposedat right angles to the main body portion of the contact plates, and arelaterally offset -from the main body portion of the plates for a reasonwhich will be made clear presently.

The mounting base in the form here shown comprises two moulded parts It:and i6 secured together by means of two screws 11 which pass throughclearance holes provided in opposite corners of the lower moulded part land are screwed into threaded inserts 18 provided in the upper mouldedpart It. The remaining corners of the two moulded parts are providedwith vertically aligned holes H which align with inserts [8 provided inthe part l6 through which screws or bolts may be passed to secure thebase to a mounting rack or other convenient support.

The mounting base is adapted to partially enclose the asymmetric deviceto protect it from injury, and for this purpose the upper moulded partIt is formed with a semi-cylindrical recess 2. having a radius oicurvature slightly larger than the radius of curvature of the asymmetricunits, and a depth sumcient to receive the major portion of theasymmetric device. A plurality of slots 2| are provided in the part IIon opposite sides of this recess in positions to receive the prongs aand b of the asymmetric device when the device is lowered into therecess 20, and these slots each communicate at their lower ends with arecess 22 formed in the part It directly below the associated slot.Disposed in each recess is a female contact clip or connector 23 whichis adapted to engage the contact prongs on the device when they areinserted into the slots 2| and thereby make electrical contacttherewith. The connectors may have any desired construction, but as hereshown each connector comprises two separate contact members, each havinga tail portion 23a and a body portion 23b disposed at right angles tothe tail portion. Each body portion is formed with a U-shaped returnbend so constructed that when the con tact members are in place in theslots 22 their inner legs are urged toward each other due to theirinherent resiliency. The connectors are inserted into the recesses 22before the part it is secured to the part i5 and are held in place inthe recess by the part IS. The tail portions 23a of the connectorsproject through the side of the mounting base, and are provided at theirouter ends with through holes 23d, and with notches 23c to facilitatesecuring circuit wires to the connectors.

In constructing asymmetric devices of the type described it is extremelydiflicult to cause the contact plates 4, 5 and 6 to always be spacedapart the same distance for the reason that the thickness of the oxidecoating on different units A varies even when the units are made underthe most exacting conditions, and for the further reason that when thenut 3b is tightened, the impressionable metal in the washers 1 tends toflow a, slight amount which amount varies somewhat in diflferentdevices. In order to allow for this variation in spacing between thecontact plates, and still permit the device to be readily plugged intothe mounting base, the contact prongs a and b are disposed at rightangles to the plane of the plates in the manner previously described,and the slots in the mounting base through which the prongs extend havebeen made longer than the width of the prongs by an amount which is atleast equal to the difierence in spacing between the plate encounteredin practice.

It should be particularly noted that with this arrangement of the prongsand slots, variations in the spacing between the contact plates does notchange the contact pressure between the contact prongs and the circuitconnectors in the base as might happen for example if the prongs weredisposed in the same plane as the contact plates and the connectors wererotated through an angle of from the position shown.

When the device is plugged into the mounting base, it is desirable toprevent it from being displaced, due for example, to vibration, and forthis purpose one of the contact plates, here shown as the middle contactplate 6 is provided with. a locking prong 24 which projects into alignedslots 25 and 26 formed in the two base parts l5 and I6, and cooperateswith a hair pin spring 21 disposed in a recess 28 formed in theunderside of the upper part 16 of the base. When the prong 24 is inplace in the slots 25 and 26, the legs of the spring, due to theirinherent resiliency enter notches 28a formed in the opposite sides ofthe locking prong and thus grip the prong to thereby latch the device inplace in the base. The spring 21 is maintained in the desired positionin the recess 28 by depending rounded projections 29 moulded on the partit and extending into the recess in the manner shown. To facilitateforcing the two legs of the spring apart when the locking prong is beinginserted into the aligned slots 25 and 26, the lower end of the lockinprong is pointed as shown.

In at least one application of asymmetric devices of the type describedeach leg of the device is connected in multiple with the winding of adifferent relay, and the construction of the device described enablesall circuits for the relay windings to be completed through the contactplates of the device, whereby when the device is removed from themounting base, the relay cir- 2o edits are all open, thus insuringagainst false circult operation due to the removal of the asymmetricdevice from the circuit.

The eifective resistance of the device between 25 the middle and twooutside contact plates depends upon the number of units connected in Vseries between the plates. It is sometimesdesirable to be able toassemble a greater number of units in each leg of the device to change30 its resistance characteristics, and still be able to plug the deviceinto the same mounting base.

between the contact plates can be provided by removing the spacerwashers I provided in the two legs of'the stack.

If a smaller number of units are desired betwmn the contact plates,additional spacer washers may be provided sumcient in number to maintainthe spacing between the plates necmsary to enable the device to beplugged into the moun base.

though we have herein shown'and described two forms of etric devicesembodying our invention and one form of mounting base therefor, it isunderstood that various changes and modifications may be made thereinwithin the scope of the appended claims without departing from thespirit and scope of our invention.

minal members in laterally oitset relation in such manner that byturning the terminal members around in the stack the distance betweenthe ter- 4 minal members can be changed to provide a greater or lesserspace for asymmetric units between them without changing the distancebetween the contact prongs, whereby the same mounting base can be usedfor different devices having difleront numbers of asymmetric unitsincluded therein.

2. An asymmetric device comprising a stack of asymmetric units, terminalmembers disposed in 0 said stack and provided with contact prongs, a

mounting base provided with slots for receiving said prongs and withrecesses communicatin with said slots, and circuit connectors disposedin said recesses and adapted to engage said prongs to make electricalcontact therewith, said prongs being disposed in planes extendingparallel to the axis of the stack and said slots being made longer thanthe widths of the prongs and the engaging surfaces of the circuitconnectors being disposed in longitudinal alignment, whereby the prongscan be inserted into engagement with the circuit connectors withoutdistorting the parts irrespective of slight diflerences in thelongitudinal spacing of the contact prongs.

3. As a new article of manufacture an asymmetric device provided withterminal members having contact prongs for plug-in engagement with amounting base, said contact prongs being disposed at right angles to andlaterally oil-set from the plane of the main body portion of theassociated terminal member for the purpose set forth.

BRANKOLAZICH.

1 RI H.

